1. Field of the Invention
The present invention relates to door sealing mechanisms and, in particular, to a device for securely locking and sealing a door of a pressure vessel.
2. Description of the Invention Background
In various applications, a door must be securely fastened to a door frame. In those applications where a door is provided for a pressure vessel, the door must be secured to various points on the door frame of the pressure vessel to assure a balanced loading of the frame by the force of the pressure to allow complete door sealing. For example, in a sterilization apparatus in which the sterilization chamber is pressurized, a suitable door fastening mechanism must be provided to assure uniform door loading to guarantee complete door sealing during chamber pressurization.
Heretofore, various mechanisms have been provided for the securing of a door of a pressure chamber to the frame of the chamber. In certain of these mechanisms, retaining hooks or notched hook bars are provided on both sides of the door frame which are engaged by bars mounted for horizontal sliding movement on the door. The hooks extend inwardly over the door so that the bars may be laterally moved into engagement under the hooks to provide backing support for the bars and, hence, the door, against the pressure within the chamber. However, in such installations, the door is typically mounted for vertical movement between one elevation in which the door may be opened or is in facing relation but not sealed to the end frame and another lower elevation in which the door is in a position sufficient to engage the hooks or hook bars. It will be readily appreciated that in such systems the door must pass through a considerable change in elevation between the upper openable position and the lower position in which the bars may engage the hooks or hook bars. This elevational difference is necessary in order for the notches in the door to clear the hooks or notches in the hook bars. The mechanisms employed to raise the door such a distance must be inordinately massive to allow for the considerable vertical movement of the door thereby significantly increasing the cost and complexity of the door's mechanisms.
Another problem has become apparent in structures where stationary hooks or hook bars are employed on the end frame of the shell to resist the pressure within the chamber. Due to the extension of the stationary hooks or hook bars over the door edges, the door must be constructed wider than otherwise necessary outside the area of the door-mounted seal so that the hooks may engage the door and the ends of the hooks will not interfere with the seal when the door is opened. This oversizing increases the envelope width of the apparatus which translates into a smaller chamber that may be used in a given space. Further, the added door width causes an increase in the bending moment of the arm from the hinges on the door frame which increases the structure of the shell and, hence, the cost thereof.
The subject invention is directed toward an improved means for securing a door of a pressurizable chamber which overcomes, among others, the above-discussed problems and is effective to secure the door without requiring its undue lifting and the costs associated with the mechanisms for doing so.